“While Facebook provides a valuable service to users by keeping them connected with friends and family and reconnecting them with long-lost friends and colleagues, the expansion of Facebook – both in the number of users and applications – raises new concerns for users who want to maintain control over their information,” the letter said.

The senators, who staged a press conference in Washington, D.C., Tuesday afternoon, said they supported a request made by Schumer during the weekend for the Federal Trade Commission to examine initiative the Palo Alto firm launched last week to extend Facebook’s social networking presence to all parts of the Web.

A Facebook spokesman said the company has not yet received the letter from the four senators and had no immediate comment.

But in a written response to Schumer, Elliot Schrage, Facebook’s vice president of global communications, marketing and public policy, invited Schumer’s staff to a meeting to discuss how the latest changes “will result in more control for users, not less.”

“These new products and features are designed to enhance personalization and promote social activity across the Internet while continuing to give users unprecedented control over what information they share, when they want to share it and with whom,” Schrage wrote. “All of Facebook’s partner sites interact with a user’s consent.”

Tuesday’s letter to Zuckerberg raised three issues, starting with a call to give Facebook members the first choice to make their profile information public instead of having that done by default.

The senators also ask Facebook to reverse a change that allows third-party advertisers the ability to store profile data indefinitely instead of just 24 hours. Facebook officials said last week that change was needed to make the platform run smoother for third-party developers.

The senators also called for Facebook to make the process of opting in to a new “Instant Personalization” program more “clear and coherent.” That program launched with three partners, software giant Microsoft, Internet radio service Pandora and online review site Yelp.